Exchanges of carbon-and nitrogen-trace gases(e.g.,CO2,CH4,N2O,NO,NH3,HONO,VOCs)commonly occurs between land ecosystems and the atmosphere.They are widely concerned because some of these matters are greenhouse gases(GHGs)whiles the others are direct or indirect air pollutants.Furthermore,in addition to productivity services,land ecosystems also influence water quality via hydrological nitrogen losses.Therefore,management of land ecosystems is expected to aim at multiple goals,including mitigation of GHGs,gaseous air pollutants and hydrological nitrogen loads and sustain of productivity,so as to protect food security,ecosystem health,air quality and water quality,and combat environment/climate changes.However,best ecosystem management are still severely limited by a number of challenges.